I meant compared to each other, then yes 1.5 is a lot older (and bigger) compared to Perry.

Bit of a problem. Sometime early this morning Lapis' filter stopped working. I've tried everything (different power point/adaptor etc) but can't get it happening. I have to leave ona work trip tomorrow and while flatmate has instructions I'd like to have at least *something* in his tank. It had cycled so I worry if the bacteria die off then the tank will crash. I do have small sponge filter, do you think it will be enough to get by until I'm back?

She can look n and change his water if necessary. I'll be gone 5 full days. Change water before I leave and as soon as I get back. :(

The impeller? Yes, I tried but it's inside the filter and I can't see any way to open it without breaking it. Got a sponge filter in there for now, along with some stuff from the other tank to encourage the bacteria to colonise in there... fingers crossed...

It doesn't have one of those. It's a very simple filter. For now, I have the sponge filter in. I was torn between having it, since it makes alot of bubbles and Lapis doesn't like those, or not having it and risking the junk to build up over 5 days. I've been watching him and he seems ok with it now, cruising around.

On the other hand, if I knew 5 days without a water change wasn't going to kill him, I'd prefer to leave the bubbles off to keep it calmer. But, my gut tells me to have at least some kind of filter going...

depending on how many tetras you had you probably would have been fine without the filter for 5 days seeing as its an 8 gallon tank, but you have a much better chance of not needing to cycle your tank again with the sponge filter in there for now.